Impaired oxygen extraction in metabolic myopathies: Detection and quantification by near-infrared spectroscopy

• Published in: Muscle & nerve Vol. 35; no. 4; pp. 510 - 520
• Main Authors: Grassi, Bruno, Marzorati, Mauro, Lanfranconi, Francesca, Ferri, Alessandra, Longaretti, Miriam, Stucchi, Andrea, Vago, Paola, Marconi, Claudio, Morandi, Lucia
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.04.2007; Wiley
• Subjects: Adult; Adult and adolescent clinical studies; Aged; Biological and medical sciences; Diseases of striated muscles. Neuromuscular diseases; Energy Metabolism - physiology; Exercise - physiology; Exercise Test; Exercise Tolerance - physiology; Female; Glycogen Storage Disease Type V - diagnosis; Glycogen Storage Disease Type V - metabolism; Glycogen Storage Disease Type V - physiopathology; Heart Rate - physiology; Hemoglobins - analysis; Hemoglobins - metabolism; Humans; Male; Medical sciences; Mitochondrial Myopathies - diagnosis; Mitochondrial Myopathies - metabolism; Mitochondrial Myopathies - physiopathology; mitochondrial myopathy; Muscle, Skeletal - metabolism; Muscle, Skeletal - physiopathology; Myoglobin - metabolism; myophosphorylase deficiency; near-infrared spectroscopy; Neurology; oxidative metabolism; Oxidative Phosphorylation; Oxygen Consumption - physiology; Predictive Value of Tests; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Psychoses; Reference Values; Schizophrenia; Spectroscopy, Near-Infrared - methods; Spectroscopy, Near-Infrared - trends; Human; Nervous system diseases; Oxygen; Glycogenosis V Mac Ardle; Deficiency; Tolerance; Cardiovascular disease; Metabolic diseases; Lower limb ischemia; Enzymopathy; Congenital disease; Genetic disease; Psychosis; Vascular disease; Striated muscle disease; Mitochondria; Biopsy; Negative symptom; Carbohydrate; Mitochondrial myopathy; Oxygenation
• ISSN: 0148-639X; 1097-4598
• DOI: 10.1002/mus.20708

Patients with mitochondrial myopathies (MM) or myophosphorylase deficiency (McArdle's disease, McA) show impaired capacity for O2 extraction, low maximal aerobic power, and reduced exercise tolerance. Non‐invasive tools are needed to quantify the metabolic impairment. Six patients with MM, 6 with McA, 25 with symptoms of metabolic myopathy but negative biopsy (patient‐controls, P‐CTRL) and 20 controls (CTRL) underwent an incremental cycloergometric test. Pulmonary O2 uptake (V̇O2) and vastus lateralis oxygenation indices (by near‐infrared spectroscopy, NIRS) were determined. Concentration changes of deoxygenated hemoglobin and myoglobin (Δ[deoxy(Hb + Mb)]) were considered an index of O2 extraction. Δ[deoxy(Hb + Mb)] peak (percent limb ischemia) was lower in MM (25.3 ± 12.0%) and McA (18.7 ± 7.3) than in P‐CTRL (62.4 ± 3.9) and CTRL (71.3 ± 3.9) subjects. V̇O2 peak and Δ[deoxy(Hb + Mb)] peak were linearly related (r2 = 0.83). In these patients, NIRS is a tool to detect and quantify non‐invasively the metabolic impairment, which may be useful in the follow‐up of patients and in the assessment of therapies and interventions. Muscle Nerve, 2006